1. Field of the Invention
The present invention relates to an ink jet recording method for recording images by ejecting ink in response to electrical signals, and to an ink jet recording method that satisfies requirements for ink jet recording such as, in particular, high printing quality and compatibility with regular paper and an ink jet liquid composition used in the method.
2. Description of the Related Art
The principle of an ink jet recording method is ejecting liquid ink or molten-solid ink from nozzles, slits, porous films or the like onto paper, cloth, film or the like. Various methods including the so-called electric charge-control method in which ink is ejected by using electrostatic attraction, the so-called drop-on-demand method (pressure pulse method) in which ink is ejected by using vibration pressure of a piezoelectric element, the so-called thermal inkjet process in which ink is ejected by using pressure caused by air bubbles generated and grown at high temperature, and the like, have been proposed as methods for ejecting ink, and thus these methods make it possible to form extremely high-definition images.
For example, an ink jet recording device that records images by ejecting liquids including at least an ink and an image-quality improving solution, which improves quality of the recorded images by being contacted or mixed with the ink, onto a recording medium according to input image data, and that is provided with an ejection data-calculating means that calculates an amount of the ejected liquid containing the image-quality improving solution from the amount of the ejected ink to form the images on the recording medium has been proposed, and extremely high-definition images are realized by this ink jet device (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 8-216386).
Inks for the ink jet recording methods include aqueous dye inks wherein various water-soluble dyes are dissolved in liquid media containing water and a water-soluble organic solvent, aqueous pigment inks wherein various pigments are dispersed in liquid media containing water and a water-soluble organic solvent, oil-based dye inks wherein oil-soluble dyes are dissolved in organic solvents, and the like. Among these inks, aqueous dye inks and aqueous pigment inks have become the mainstream of ink jet recording inks, because the main solvent thereof is water and the inks are thus superior in safety.
Further, there are many requirements for the liquid compositions including the above-described inks for ink jet recording, and specific examples thereof include: (1) no clogging in nozzles of ink jet recording heads; (2) superior ejection stability and frequency responsiveness; (3) good recovery of smooth ink ejection after being left for a long time; (4) no generation of precipitates even after long-term storage; (5) no causing of corrosion-deterioration of members, such as the recording heads, which contact therewith; (6) provision of favorable printing quality; (7) safety and no unpleasant odor; and the like.
Recently there is a great demand for printed images having photo-like quality by using the ink jet printing technology, and development of higher resolution of printed images by using an ink jet recording method which uses ink droplets having smaller size is in progress. Further, ink jet printers are spreading widely in business applications because of advantages such as lower noise and lower running cost, and printing speeds higher than those of printers using an electrophotographic process have come to be desired. Thus, an ink jet recording method that satisfies requirements such as high water resistance, high speed printing, suppression of blurring and especially blurring between colors, and liquid compositions and the like for use in the recording method have come to be desired.
The drying property of the ink on paper media (recording media) must be improved for use in the above-described high-speed printing. In particular, a printed face of a printed paper medium discharged after being printed must not be stained by being stacked onto and rubbed against a printed medium that has been previously discharged.
It is possible to suppress the blurring between colors by, for example, ejecting as small ink droplets as possible and dividing the printing data so as to print images by plural head scanning. However, such a technique includes the problem of a decrease in printing speed per page.
Incidentally, an example that uses a chitosan derivative having a colorant structure at the side chain thereof as a constituent material for the liquid composition has been proposed (see, for example, JP-A No. 8-283640). However, the chitosan derivative is costly as it is prepared in a synthetic process, and further, the chitosan derivative cannot provide recorded images with sufficient storage stability. Further, an example that contains a succinylated carboxymethylchitosan and a lactic acid has been also proposed as the constituent material (see, for example, JP-A No. 9-95636). However, the composition is not sufficiently effective in suppressing blurring. Furthermore, an example that contains a polymer that is reactive with chitosan salts has been also proposed as the constituent material (see, for example, JP-A No. 2002-2087). However, the composition cannot provide a sufficient ejection stability due to increase in the viscosity of ink.
As described above, there are currently no ink jet recording inks that can satisfy the various requirements in performance for the ink jet recording method. In particular, conventional ink jet recording liquids (inks) having high drying speed do not provide sufficiently advantageous effects even in combination with various processing solutions.